Drop table



Oct. 226, 1937. 1 RICHARDSON DROP TABLE Filed Jan. 4, 1935 4Sheets-Sheet l NVENTOR.

m@ mw, RN QN ww W I h y@ FL uw mw mw W 10% Q @s D. iii w @A Y .I I l w s5%.@ wh A Oct, 26', 1937. RICHARDSON DROP TABLE Filed Jan. 4, 1935 4Sheets-Sheet 2 IN1/EN 0R.

ATTORNEYS Oct. 26, 1937. I R|CHARDSQN 2,097,133

DROP TABLE Filed Jan. 4, 1955 4 sheets-Sheena a o o ia yf Oei. 26, 1937.L, RlCHARDSON 2,097,133

DROP TABLE Filed Jan. 4, 1935 4 Sheets-Sheet 4 Patented Get. 26, 1937STATES PATENT orig 11 Claims.

This invention relates to equipment for lowering and raising relativelyheavy loads` such, for example, as are encountered in the removal of thewheels of a locomotive and, inasmuch as the in- Vention has beendeveloped with locomotive requirements in view, the embodiment disclosedherein is particularly useful in unwheeling locomotives.

The particular objects and advantages of the invention will probably bebetter understood if brief reference is first made to the practices ofthe art as it exists today. For example, the most familiar form ofequipment for removing the wheels of a locomotive is probably the onewhich is known as the hydraulic drop pit. With this apparatus thevehicle is first jacked up in order to remove its weight from thewheels, after which a hydraulic plunger is brought up under the centerof the axle of the pair of wheels which is to be removed. The axle isthen raised slightly so as to permit lateral removal of the sections ofthe rail upon which the whe-els had been resting. After the rails arewithdrawn, the plunger is dropped in order to lower the axle and itswheels.

The disadvantages of the foregoing equipment are rather numerous. In thefirst place, the hydraulic mechanism is not susceptible to accuratecontrol nor is the device satisfactory from a safety standpoint for thereason that the axle with its wheels is merely balanced on the top ofthe plunger and frequently slides off. This is especially likely tooccur during the operation of returning the wheels to their positionunder the locomotive because, if they do not happen to be accuratelycentered on the plunger, one end orthe other may catch upon some portionof thev mechanism and cause the axle to tip and slide off. Besides thedanger involved in injuring the equipment, many serious accidents toworkmen have resulted from just such an occurrence.

Another objection to the hydraulic pit is the fact that the pit must betwice as deep as the drop for the plunger, which, of course, increasesthe cost and difculty of installation. Furthermore, in hydraulicmechanisms more or less leakage is always present which makes the pitssloppy and wet and greatly adds to the hazard.

Another type of device which is very well known to the art at thepresent time is one which involves the use of a table mounted on fourscrews, one at each corner and, while tables of this kind have beenarranged to carry that portion of the entire weight of the vehicle whichis borne by the wheels to be removed so as toavoid the necessity ofjacking up the locomotive, yet thisr feature has introduced a seriousdisadvantage in that the power demanded of the prime mover variesextensively, namely, from that degree of power which is necessary tosupport the full load of the axle down to that which is necessary to isupport merely the axle with its wheels. Furthermore, tables of thiskind when in their full lowered position have an appreciable height orthickness, that is, the distance from the rail to the bottom of the pitis` relatively great.

With the foregoing in mind, the objects of m invention will be betterunderstood, the principal ones being as follows:

1. The provision of a greatly simplified drop table equipment and onewhich is more economical to manufacture, install and maintain;

2. The provision of a drop table which in collapsed or lowered positionwill have a much reduced vertical dimension;

3. The provision of equipment of the character L described in which thepower demandsy upon the prime mover are maintained as nearly constant aspossible so as to avoid the necessity for using an extremely powerfulmotor;

4. The provision of a drop table the operation of which is lesshazardous than tables heretofore in use, as well as one which isimmediately locked in position should the power fail for any reason;

5. The provision of equipment of the screw type in which the screw iswell protected so as to avoid all damage thereto during operation of thedevice;

6. The provision of a table having pivoted legs, together with means forswinging the legs on their pivots in order to raise or lower the table;and

7. The provision of equipment of the character described in which isemployed a combinatio-n of lever or toggle-actuating mechanisms incombination with cam surfaces which cooperate to greatly reduce thevariation in power demanded from the prime mover.

How the foregoing objects, together with such other objects as mayappear hereinafter or are incident to my invention, are obtained isillustrated in the accompanying drawings which disclose a preferredembodiment of the invention particularly suitable for use in unwheelinglocomotives as above mentioned.

In the drawings:

Figure 1 is a side elevation of my improved drop table equipment.

Figure 2 is a plan view.

Figure 3 is an end elevation from the righthand end of. Figures 1 and 2,showing the device g in position in a pit, with the pit, the guides atthe sides, and the tracks in the bottom shown in section. f

Figure 4 is a plan View of one of the tracks in the bottom of the pit,showing the arrangement of cams which I employ.

Figure 5 is a diagrammatic View on a reduced scale showing the parts inraised, partly lowered, and fully lowered position in the pit, the pitbeing shown in vertical-longitudinal section; and

Figure 6 is a graph illustrating the character of the operation securedwith my improved device.

Inspection of the drawings will show that the top of the table isconstructed as a supporting framework comprising essentially theparallel sections of rail 1, which run transversely of the table, andthe longitudinally extending H-beams 8, the rails being suitablyrecessed topass-the H-beams 8, and the parts being welded together whenassembled. The ends of the rails 1 are cut back, as shown at 9 in Figure3, -in order to leave the lower projecting portions I0 which extend intochannel-shaped guides lII which are suitably secured to the upperportions of the side walls of the pit I2. The guides are slightly flaredat the bottom, as at I3, and they slope upwardly and inwardly, as bestshown in Figure 3, in order to accurately guide the ends of the rails totheir proper position when the table is raised from its lowered positionto its extreme up-ward position. In this upward'position, the extensionsI0 on the rails 1 t under complementary extensions I4 on the adjacentrail sections 1a, which latter, of course, are part of the permanenttrack associated with the drop table mechanism.

The upper framework of the table just described is supported upon fourlegs I5 which are pivoted under the ends of the rail section 1 by meansof the rail chairs I6. There is one chair YI6 for each leg I5, and thetop of each leg is bifurcated in order to straddle the downwardlyprojecting tongue I1 of the chair, Vthe parts being held together bymeans of pivot pins I8.

The two legs I5 at the left-hand end of theV table, as viewed in Figures1 and 2, are bracedtogether near the bottom by means of any suitableinterconnecting member I9, and those at the right by means of theinterconnecting member 29, the parts being secured together in anydesired or suitable manner. Longitudinally of the table, the legs ateach side are connected together and, therefore, constrained to move inunison by means of the channels 2l pivoted to the legs at the points 22and 23.

The two legs at the right in Figures l and 2 are equipped at the bottomon the inside with rollers 24 mounted upon the cross-shaft 25, while thetwo legs at the left are equipped on the outside with rollers 26Ymounted upon the cross-shaft 21.

The rollers are held in place by Cotter pins 28. The rollers travel overangle-shaped trackways 29 which are provided with the camY surfaces 39,the function of which will appear more fully hereinafter. It should benoted, however, that there is one cam 30 for each leg I5 and that thecams for the right-hand legs are located to the inside of the trackwaysand those for the left-hand legs to the outside of the trackways', sothat the cams for th-e left-hand legs, which are at the outside of therollers, will not interfere with the rollers 24 on the right-hand legs,which rollers 24 are located on the inside of the trackways 29. In otherwords, each leg with its'roller is intended Vto roll over one cam onlyand not over two successive cams. I

It will be clear from the description thus far given that the table topor frame for supporting the load, composed primarily of the railsections 1 and the H-bearns 8,`may be raised or lowered by swinging thelegs I5 on their pivots I3. I will now describe that portion of themechanism which is provided for so swinging the legs.

As will be seen upon inspection of Figures 1 and 2, the H-beams` 8project laterally beyond the left-hand rail 1, and upon suitablebrackets 3l which span the distance between the beams 3, I mount a powermeans such as the reversible electric motor 32 which is adapted to drivethe operating screw 33. The motor shaft 34 is connected to the screw 33by means of the sleeve '35 whichis splined to the shaft 34 by the key 35and non-rotatably connected to the screw 33 by the pin 31. The sleeve 35is provided with the annular shoulder 38 which lies between two bronzebearing' rings 39. The shoulder 38 and the rings 39 are embraced in acup-shaped housing 49 which is carried in any suitable manner by thebottom of the rail 1. After assembly, the open end of the housing 40 isclosed by means of the thrust bearing plate 4I which is held in place bythe bolts 42.

The free end of the screw 33 is threaded into the central block 43 inthe operating cross beam 44 which is arranged to slide longitudinally ofthe tableupon the guides 45 which are attached to the under side of thebeams 8. The ends of the beam 44 are bifurcated as at 4B (see Figure l)yin order to embrace the shafts of the turnbuckles 41 which are securedbetween the bifurcations by means of the pins 48. It will be understood,of course, that the cross arm 44 may be moved one way or the other bymeans of the screw 33, the arm moving along the screw as it rotates. InFigures 1 and 2, the arm 44 is shown at its extreme right-hand position,in which position the legs I5 are upright and the table is in its raisedposition. The legs are moved by means of the operating cross bar 44through the mechanism now to be described.

At the left-hand end of the beams 8 are provided two crank devices inthe form of sectorshaped sheaves 49 having xed thereto the crank arms50. These sheaves are mounted upon the projecting ends of a pivot rod 5Iwhich extends between the beams 8. The ends of the cranks arearticulated upon pins 52 to the ends of connecting rods 53, the otherends of which connecting rods are pivoted upon the pins 22 to the legsI5. The sheaves 49 are free to rotate on the pivot rod 5I, and it willbe seen that movement in a counter-clockwise direction will raise thecranks50 and pull on the rods 53 in order to swing the legs I5 to theleft on their pivots IB and thereby lower the table.

The sheaves are rotated in unison by means ofthe operating cable 54which serves to insure uniform movement of all of the parts includingparallel operation of the bar 44 by virtue of the fact that thiscable'is continuously reeved between the ends of the bar 44 and aroundthe sheaves 49 from one side to the other of the table in a mannersimilar to Vthat which is employed in the operation of a parallel rulerfor a drawing board.

To be more specific, the cable is connectedin the following manner.Beginning, for example, with the turn-buckle 41 at the upper side ofFigure 2, the cable extends to theright around the lower sheave 55 whichis held at a slight angle by means of the supporting bracket 55 so thatin rounding the sheavethe cable will leadV to the up-per sheave 51 onthe other side of the table, from whence it extends to the inner'grooveof the double-groovecl sheave 58 and then downwardly and around theinner groove of the crank sheave 49 on the lower side of the table, asviewed in Figure 2; The cable then comes upI and around the sheave 49and passes through an opening 59 in this sheave and through they guidering 60 to the top of the outside groove in the sheave` 49, and fromthis point it extends downwardly and under the outside groove in thesheave 58, and then back to the turn-buckle 41 on the lower side of thebeam 44, as viewed in Figure 2. Continuing from this point, the cableruns around the sheave 55a across to the sheave 51a, and then back tothe inner groove of the sheave 58a from whence it passes downwardly andunder the inner groove of the sheave 49 on the opposite or upper side ofthe table, as shown in Figure 2. This sheave 49 is the same inconstruction as the sheave 49 at the other end of the rod 5|, exceptthat the parts are reversed. The cable comes up and around the innergroove and then through the opening in Vthis sheave and outwardly andupwardly over the outer groove in the sheave and then downwardly andunder the outer groove in the seave 58a, and so on back to the point ofbeginning at the turn-buckle 41 on the upper side of the table, asviewed in Figure 2.

The cable, therefore, is in reality a continuous cable which is reevedbetween the two sides of the table and secured at two points in itslength to the opposite ends of the cross beam 44.

As stated, the sheave 55 is held in place by a suitable bracket 56 as isalso the sheave 55a. The sheaves 51 and 51a are held in place bybrackets 6 l, and the sheaves 58 and 58a are mounted upon suitable pins62 which project from the side of the beams 8.

The operation of the parts so far described'will now be briefly setforth. Assuming that the table is in its raised position, as shown inFigures 1, 2, and 3, and that a lowering operation is desired, the motoris started in the direction necessary to rotate the screw 33 so that thearm 44 will be drawn tothe left. This, of course, will pull on the cable54 at the two points 48, causing movement around the various sheaves insuch a way as to rotate the crank sheaves 49A in a counter-clockwisedirection, so that the crank arms 50 will pull on the connecting rods 53in order to swing the legs I5 on their pivots I8 and thereby collapsethe table.

As the legs swing, the rollers 24 and 26 at their bottomsV will passover the cams 38 which cooperate with the Yvarious lever mechanisms insuch away as to greatly reduce the variation in power demanded fromrtheprime mover or motor 32. This will be more apparent upon inspection ofFigures 5 and 6. i

When the table is in its upright position, as shown in full lines at theright-hand side of Figure 5, it will, of course, carry the entire weightof the axle 63 with its wheels 64, shown in dotand-dash lines inposition upon the rail sections l. This weight or load in certain of thelarge size locomotives of the present may amount to approximately 50,000pounds per axle, so that at this moment the table is supporting 50,000pounds of load, as shown in the graph of Figure 6. The rollers 24 and26, however, do not reach the cams 30 until after the table is droppedapproximately two inches, let us say. The power necessary at this pointwhen the upward incline of the cam surfaces is eiective is approximately8,000 pounds, as shown in the graph, and during: the. next ten inches oftravel of the table downwardly from its raised position, or, namely,

Auntil the table has been lowered twelve inches,

the powerv required on the toggle operating mechanism" is approximatelyconstant, namely, 8,000 pounds. The peak of the cams is reached afterthe table `has been collapsed twelve inches, as shown in the graph, and,of course, the power required immediately drops sharply, so that in thenext two inches as the rollers ride down the far side of the cams 38,the power required from the toggle operating mechanisms drops tosomething under 5,000A pounds, and from here on there is a steady dropthroughout the balance of the lowering movement which, in the presentinstance, is assumed tobe approximately thirty inches. After the thirtyinch drop, the power required on the toggle is only approximately 1,500poundsi During this time, the load, of course, drops very quickly fromits total of 50,000 poundsy .down to its total of approximately 2,500 or2,600 pounds during the first five inches of travel of the table in adownward direction. From here on tothe end of the downward movement, theload carried by the table, of course, is constant, since the only weightis the weight of the axle with its wheels and associated parts. The loaddoes not come down to its minimum,-

Vnamely, 2,500 or 2,600 pounds, until after the springs normally used insupporting the weight of a locomotive are completely unflexed. Thisoccurs after the table has travelled downwardly approximately iiveinches and, when it occurs, the load, of course, immediately becomesconstant throughout thel balance of the motion of the table.

In raising the table just the reverse action takes place, and it will beseen upon analysis of the graph in Figure 6 that I have sol-arranged thetoggle and crank operating mechanisms in their relation to the camsurfaces as to reduce to a minimum the variation in powerV demanded ofthe prime mover.` According to the graph, which represents averageconditions, this power demand vares approximately from 1,500 pounds to8,000 pounds, while, in previous tables of the screw type, thisvariation has been. from ap. proximately 2,000 pounds to 50,000 pounds.

Referring specifically to Figure 5, I should like to'point out that whenraising the table there is a net upward movement of the table of onlytwo inches between the time that the rollers 24 and 26 are at the highpoints of the cams 30 and the time that the table is fully raised, asshown in full lines. During this time, however, I arrange to applyapproximately 40% of the movement of the-primary power mechanism so thatthe leverage obtained is exceedingly great and requires only anapplication of power never exceeding approximately 8,000 pounds underthe conditions of load assumed. The first 60% of the movement of thepower mechanism occurs as the table moves from its lowered positionapproximately twenty-eight inches of its upward motion, and during thistwenty-eight inch movement and just before the. complete load of thelocomotive is taken by the table, the rollers 24 and 26 ride upward tothe high point of the cams 38. Therefore, the amount of power necessaryto move the rollers over the cams during a raising operation is neverexcessive, and the arrangement is such as to make available a muchgreater degree of power at the time when it is 'actuallyneededg namely,during'lthe last couple of inches of movementl ofthe table. when thetable begins to assume the full load of the portion of the locomotiveassociated with vthe axle and wheels which it is carrying.

It will be understood, of course, lthat the upper ends of vthe legs I5are guided inthe channels ii so that'they move in a straight up-anddowndirection until such time as the lowering operation has gonesuiiiciently far to bring the ends of the rails 1 below the channels Il.When this occurs, the table is practically in its full lowered positionandcan be movedto the left, as shown in dot-and-dash lines. in Figure 5.When in the left-hand position the table can, of course, be raised inorder to bring the rails 'l in line with the rails 'l' so that thewheels may be rolled off in order to receive whatever work they mayrequire. The dot-and-dash line position at the left of Figure 5represents the completely collapsed position of the table,A and thedot-and-dash line position at the rightV of Figure 5 represents theposition of the parts at the time that the rollers 24 and 26 are atthehigh points on the cams 30.

I claim: Y

' l. A drop-table comprising inv combination, a frame for receivingtheload, a pair of Vlegs at each side of the frame pivoted thereto,means constraining the two legs of each pair to move in unison, anoperating crank for each pair of legs whereby the legs may be swung ontheir pivots to lower'or raise the frame, and a power means including amovableY Cross beam,'and cable means connected to the-beamand 'reevedbetween the two cranks. l

2.V A drop-table comprisingin combination,` a frame for receiving theload, supporting legs pivoted to the frame, crank means on the frameadapted to swing said legs on their pivots to lower or raise the frame,a power means carried by the frame, and cable means reeved between thepower means and said crank means.

3. AVdrop-table comprising in combination, a frame for receiving theload, supporting `legs pivoted to the frame, a movable cross beam, amotor for moving said beam, a crank connected to the legs on one side ofthe frame, a second crank connected to the legs on the other side of theYtrarne, and a continuous cable means connected to the ends of said beamand reeved between the cranks.

4. A drop-table having asupporting means ivoted to each of two oppositesides thereof whereby the table may be raised and lowered, an operatingcrank for each of said pivoted supporting means, a power means includinga movable cross beam, and an endless cable means for actuating saidcranks, said cable means being connected to the ends of saidrbeam andreeved between the two cranks.

5. Drop-table equipment comprising in combination, a frame for receivingthe load, supporting legsV pivoted to the frame, crank means forswinging the legs on their pivotsso as to lower the frame, means forguiding the frame during up and down movement thereof, power means formoving the crank means, and ca'm surfaces over which the lower ends ofthe legs are adapted to pass, "saidca'm surfaces being arrangedtocooperate with the. crank means in such Way as to reduce to a minimumthe variation in power requirementsover therange of movement of saidframe. Y

6. Drop-table equipment comprising in combination, `a frame forreceiving the load, sup'- porting legs pivoted to the frame, means onthe frame adapted to swing said legs on their pivots to lower orraise'the frame, guide means for the upperiends of the legs, and cammeans over which the lower ends of the legs are adapted to pass.

1 '7. A drop-table comprising in combination, a frame for receiving theload, supporting legs pivoted to the framecrank means on the frameadapted to swing said legs ,on their pivots to lower or raisethe frame,a powermeans on the frame for operating said crank means, a cable meansreeved between the power means and said crank means,.and guide means forthe upper ends of the legs.

- 8. A drop-table comprising in combination, a frame for receiving theload, supporting legs pivoted-to the frame, crank means on the frameadapted to swing said, legs. on their pivots tolower or Araise theframe, a power means on the frame for operating said crank means, acable means reeved betweenthe power means and said crank means, guidemeans for the upper endsof thelegs together with cam means over whichthe lower lends of the legs are adapted to pass.

9. Drop-tableV equipment comprising in combination, a frame forreceiving the load, supportinglegsrpivoted to the frame, power meanscarried by the frame for swinging said legs to lower or raise. theframe, and-cam means over which thelower ends ofthe legs are adapted topass, said; cam means being arranged to increase the travel of the powermeans near the upper range of movement of said frame.

10. Drop table equipment comprising in combination, a frame forreceiving thev load, supporting legs pivoted to the frame at their upperends and having their lower ends adapted to move horizontally, powermeans carried by the frame for -moving the lower ends of said legshorizontally so as to swing them on their frame pivots and thereby loweror raise the frame, guide means on the wall of the pit, and means on thetable adapted to/cooperate with said guide means to insure verticalmovement of the frame as the lower ends of the legs are movedhorizontally.

ll. Drop table equipment forrrailway vehicle axles comprising-incombination, a frame, supportinglegs pivoted to the frame at their upperends and having their lower ends adapted to move horizontally,powermeans carried by the frame forrmoving the lower ends of said legshorizontal- Ly soas to swing them on their frame pivots and therebylower or raise the frame, rails on the frame adapted to align withadjacent railway trackage, and vertical guide means on the sides of thepit with which the ends of the rail are adapted to cooperate in order toensure vertical movement of the frame as the lower ends of the legs aremoved horizontally.

LAWRENCE RICHARDSON.

